Mixer arrangement

ABSTRACT

A quadrature connected passive mixer arrangement for frequency converting analog signals from a first to a second frequency. The arrangement comprises two parallel connected mixers provided as transistors. First and second LO signals and their inverse signals having separated phases are provided for driving the transistors. Signal path switches are provided between the RF terminals and the mixer transistors. The switches are driven by signals having a different phase than the signal driving the corresponding mixer transistor. Thus, any short circuit between IF terminals of the arrangement may be eliminated.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.10/596,691, filed Mar. 8, 2007 now U.S. Pat. No. 8,060,048, which wasthe national stage filing of International Application No.PCT/EP2004/013000, filed Nov. 17, 2004, which claimed the benefit ofU.S. Provisional Application No. 60/529,984, filed Dec. 16, 2003, thedisclosures of which are incorporated herein by reference.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to an arrangement for mixing analogsignals, and more particularly to a mixer arrangement for converting afirst signal having a first frequency to a second signal having a secondfrequency.

DESCRIPTION OF RELATED ART

A mixer for frequency translating a signal having a first frequency,such as a radio frequency (RF), to a signal having a second frequency,such as an intermediate frequency (IF), is provided in a wide variety ofimplementations, such as in radio transceiver front-ends. Bluetooth® isa communication standard where the major goal has been to remove cableconnections between electrical equipment. One area, where Bluetooth® isof particular interest, is communication involving portable equipment,such as mobile terminals. The terminals may also be adapted tocommunicate according to e.g. a telecommunication technology, such asGSM, UMTS, cdma2000, PCS, DCS etc. A mixer may be necessary for theradio transceiver front-end of the Bluetooth® radio and thetelecommunication radio.

In portable communication equipment, low power solutions for allelectronic components are important. Thus, the tendency in integratedcircuit design is to apply low supply voltage for e.g. the mixer. Also,it is often required that the implementation of the mixer is cheap. MOS(Metal Oxide Semiconductor) technology offers a solution, with which ispossible to implement fully integrated mixers. However, it is essentialto find circuit architectures capable of high performance at supplyvoltages at or below 2V.

In modern radio communication architectures, such as direct-conversionand low-IF, quadrature mixers are needed. A suitable mixer topology atlow voltage and low (or zero) IF frequency is the passive quadraturemixer, which is well suited for implementation in CMOS technology. Thistopology is suitable for low voltage due to the lack of stackedtransistors, and for low IF frequencies due to the absence of flickernoise.

FIG. 1 illustrates a passive mixer, which is known in the art. Twopassive mixers comprising four CMOS transistors each are connected inparallel and operated in quadrature. Thus, each transistor will beactive when a local oscillator (LO) signal at its gate has a positivevalue. Each mixer is connected to provide signal paths from RF terminalsto first and second IF terminals through transistors controlled by acommon LO signal. At the IF terminals first and second IF signalsIF_(I), IF_(Q) are provided. The first mixer is operated by a first LOsignal LO_(I) ⁺ and its inverse signal LO_(I) ⁻ having a first phases □and □+π radians, respectively. The second mixer is driven by a second LOsignal LO_(Q) ⁺ and its inverse signal LO_(Q) ⁻ having a second phase□+π/2 and □+3π/2 radians, respectively. In operation, two LO signalswill have positive values simultaneously. Although the transistors areoperated such that the IF terminals are generating the IF signalsalternately, a path (short circuit) is created between the IF terminalsof the two mixers when any two LO_(I) and LO_(Q) signals are high. Thisis e.g. the case when LO_(I) ⁺ and LO_(Q) ⁺ have positive valuessimultaneously. This is a problem as the undesired paths between the IFterminals will ruin the gain of the mixers.

In the known art, the problem with the undesired short circuits has beensolved by providing resistors between the RF terminals and each of themixers, wherein the impedance in the paths between the IF terminalsincreases. However, this introduces another problem as it will alsointroduce additional noise. This is particularly severe for low voltagecircuits.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a quadrature mixerarrangement comprising two mixers for converting a signal having a firstfrequency to a signal having a second frequency. More specifically, itis an object of the invention to provide a mixer arrangement comprisingtwo quadrature mixers, which are isolated from each other withoutsubstantially effecting the noise performance of the arrangement.Moreover, it is an object of the invention to provide a mixerarrangement that is suitable for implementation using MOS technology.

According to a first aspect of the invention, the above objects areachieved by a quadrature mixer arrangement for converting a first signalat a first frequency to a second signal at a second frequency. Thearrangement comprises input means for receiving the first signal andoutput means for outputting the second signal. A first mixing means isconnected a first and a second terminal for inputting or outputting thefirst or second signal. A second mixing means is connected in parallelwith the first mixer and connected to the first and second terminals. Aset of switch devices is provided in the signal path between the mixersand the first and second terminals. Thus any short-circuit pathoccurring when the mixing means are at least partly conductingsimultaneously may be eliminated.

The first mixer may be arranged to be conductive for a first and/or asecond state of a mixing signal and to mix a first input signal with afirst mixer signal to provide a first output signal. The second mixer isconnected in parallel with the first mixer, and may be arranged to beconductive for a first and/or a second state of a second mixer signal.Furthermore, the second mixer is arranged to provide a second outputsignal in quadrature to the first output signal. The mixers areconnected to common first and second RF terminals of the arrangement.When transistors of the mixers are conducting simultaneously a path iscreated between a first and a second IF terminal. The set of switchdevices interrupts any potential short-circuit path between the IFterminals.

The first and second mixing signals and their respective inverse signalsare provided by four local oscillator (LO) signals, which are phaseshifted π/2 radians in relation to each other.

The first and second mixers may comprise a set of mixing means, eachhaving a first, second, and third terminal. The first mixer is adaptedto be driven by a first LO signal and its inverse signal having a firstand a third phase, respectively, received at the third terminals of themixing means of the first mixer. The second mixer is adapted to bedriven by a second LO signal and its inverse signal having a second anda fourth phase, respectively, received at the third terminals of themixing means of the second mixer.

In each mixer, first and second switch devices may be provided in thesignal path between the first terminals of the first and the thirdmixing means and the first RF terminal. Similarly, third and forthswitch devices may be provided between the second terminals of thesecond and fourth mixing means and the second RF terminal. Thus anyshort circuit between the IF terminals may be avoided.

The mixers and/or the switch devices may comprise FET transistorsprovided in CMOS technology.

The mixer arrangement may be provided either as a transmitter orreceiver mixer. In a transmitter mixer, a quadrature IF signal will beprovided as input signal and an RF signal as output signal. In areceiver mixer, an RF signal will be provided as input signal, and aquadrature IF signal will be provided as output signal.

According to a second aspect of the invention, a wireless communicationdevice having a communication interface for wirelessly communicatingwith a remote communication device, comprising the mixer arrangementaccording to the invention achieves the objects of the invention.

The device may be a portable radio communication equipment, a mobileradio terminal, a mobile telephone, a pager, a communicator, anelectronic organizer, or a smartphone.

According to a third aspect of the invention, a method of mixing signalsfor converting a first signal at a first frequency to a second signal ata second frequency achieves the objects of the invention. The methodcomprises the steps of receiving the first signal, and mixing the firstsignal in a first and a second mixing means connected in parallel to afirst and second terminal to provide the second signal. A set of switchdevices provided in a signal path between the mixers is controlled tooperatively connect either the first or the second mixer to the firstand second terminals.

The first mixing means may be controlled to be conductive for a firstand/or a second state of a first mixing signal for mixing the firstsignal with a first mixing signal to provide the second signal. Thesecond mixer may be controlled to be conductive for a first and/or asecond state of a second mixing signal for mixing the first signal withthe second mixing signal to provide the second signal. Switch devicesconnected to the first mixer may be controlled to be conductive for thefirst and/or the second state of the second mixing signal, and switchdevices connected to the second mixer may be controlled to be conductivefor the first and/or the second state of the first mixing signal.

Further embodiments of the invention are defined in the dependentclaims.

It is an advantage of the invention that the IF short circuit pathsbetween the parallel connected mixers of the invention are eliminated.Furthermore, it is an advantage that the noise performance compared withthe known art is substantially improved such that the mixer arrangementis well suited for implementation in MOS technology and may be adaptedfor low supply voltage and low (or zero) IF frequency.

It should be emphasized that the term “comprises/comprising” when usedin this specification is taken to specify the presence of statedfeatures, integers, steps or components but does not preclude thepresence or addition of one or more other features, integers, steps,components or groups thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

Further objects, features, and advantages of the invention will appearfrom the following description of several embodiments of the invention,wherein various aspects of the invention will be described in moredetail with reference to the accompanying drawings, in which:

FIG. 1 is a block diagram of a prior art mixer arrangement;

FIG. 2 is a front view of a mobile telephone and the environment inwhich it may operate;

FIG. 3 is a block diagram of a the mixer arrangement according to theinvention; and

FIG. 4 is a signaling scheme illustrating the local oscillator signalsfor controlling the mixer arrangement.

DETAILED DESCRIPTION OF EMBODIMENTS

FIG. 2 illustrates a mobile telephone 1 as one exemplifying electronicequipment, in which the mixer according to the present invention may beprovided, and a possible environment in which it may operate. Theinvention is not limited to a mobile telephone 1. The invention may beprovided in a wide variety of electronic equipment wherein a mixer isrequired for converting a first input signal having a first frequency toa second signal having a second frequency. The mobile telephone 1 maycomprise a first antenna 10 and a second auxiliary antenna 11. Amicrophone 12, a loudspeaker 13, a keypad 14, and a display 15 provide aman-machine interface for operating the mobile telephone 1. The mobiletelephone may in operation be connected to a radio station 20 (basestation) of a mobile communication network 21, such as a GSM, UMTS, PCS,and/or DCS network, via a first radio link 22 by means of the firstantenna 10. Furthermore, the mobile telephone 1 may in operationestablish a second wireless link to a peripheral device 30 via a secondwireless link 31 by means of the auxiliary antenna 11. The second link31 is e.g. a Bluetooth® link, which is established in the 2.4(2.400-2.4835) GHz frequency range. To establish the wireless links 22,31, the mobile telephone 1 comprises radio resources, which are adaptedaccording to the relevant technologies that are used. Thus, the mobiletelephone 1 comprises a first radio access means, such as a transceiver,for communicating with the base station 20, and a second radio accessmeans for communicating with the peripheral device 30.

The peripheral device 30 may be any device having wireless communicatingcapabilities, such as according to Bluetooth® technology or any otherwireless local area network (WLAN) technology. It comprises an antenna32 for exchanging signals over the second link 31, and a transceiver(not shown) adapted according to the communication technology that theperipheral device 30 uses. The device may be a wireless headset, aremote server, a fax machine, a vending machine, a printer etc. A widevariety of electronic equipment may have such communication capabilitiesand have a need for wirelessly transferring of data.

When receiving signals having radio frequencies (RF), the RF signals mayhave to be down converted to a signal having a lower frequency, such asan intermediate frequency (IF) before further signal processing isapplied. Similarly, an IF signal may have to be up converted to a signalhaving a higher frequency, such as a RF frequency, before transmitted.Thus, the radio access means of the mobile telephone 1 may comprise oneor several mixers according to the invention for converting a signalhaving a first frequency to a signal having a second frequency.

FIG. 3 illustrates a mixer arrangement according to the invention. Themixer arrangement is arranged to generate intermediate frequency signalsIF_(I) and IF_(Q) having I and Q phases, respectively, based on an RFsignal provided at RF⁻ and RF⁺ terminals, or vice versa. The arrangementis a balanced passive quadrature mixer arrangement comprising a firstand a second mixer 200, 300 connected in parallel and arranged to bedriven in quadrature. Each of the mixers 200, 300 comprises a set ofmixing devices 210, 220, 230, 240, and 310, 320, 330, 340. Here thenumber of mixing devices of each mixer 200, 300 is four. However, thenumber is only exemplary and should not be taken as limiting the scopeof the claims. The mixing means 210-240, 310-340 may comprise a FETtransistor, such as a MOSFET, which may be provided using CMOStechnology. Each of the mixing means 210-240, 310-340 provides a voltageswitch for enabling mixing of the RF signal and first and second LOsignals, or mixing of the IF signal and the LO signals. The MOStransistor has true voltage switch characteristics. Therefore, it ispossible to provide switching in the voltage domain. This makes itpossible to reduce or even eliminate the DC current flow through thetransistor, and thereby avoid the 1/f noise, which would be a problemespecially for direct conversion and low IF-receiver characteristics.

Each mixing means 210-240, 310-340 may be provided as an NMOS transistoror a PMOS transistor. The NMOS transistor has better switch performancethan the PMOS transistor due to the better mobility of electrons thanholes. Other voltage controlled switches, such as the junction fieldeffect transistor (JFET) may still alternatively be utilized as themixing means.

The topology of the first and second mixers 200, 300 is basically thesame. Thus, a first terminal of the first mixing means 210, 310 isoperatively connected to a positive RF terminal, which may be connectedto any of the antennas 10, 11. A second terminal of the first mixingmeans 210, 310 is connected to a first terminal of the second mixingmeans 220, 320. A second terminal of the second mixing means 220, 320 isoperatively connected to a negative RF terminal. A first terminal of thethird mixing means 230, 330 is operatively connected to the positive RFterminal. A second terminal of the third mixing means 230, 330 isconnected to a first terminal of the fourth mixing means 240, 340. Asecond terminal of the fourth mixing means 240, 340 is operativelyconnected to the negative RF terminal. Also, a connection is providedbetween the second terminals of the first and third mixing means 210,230, 310, 330, and thus between the first terminals of the second andfourth mixing means 220, 240, 320, 340. At said connection, IF terminalsare provided for providing, or receiving, first and second IF signalsIF_(I) and IF_(Q), as will be explained below.

Each of the mixing means 210-240, 310-340 comprises a third terminal forreceiving a signal from a local oscillator (not shown). During operationof the mixing arrangement, the RF signal will be mixed with mixingsignals, i.e. the LO signal to provide a down converted IF signal. Inuse in a transmitter arrangement, the IF signal will be mixed with theLO signal to provide an up converted RF signal. The mixer arrangement isdriven in quadrature. Thus, the first and fourth mixing means 210, 240of the first mixer 200 will in operation receive a first LO signalLO_(I) ⁺ having a first phase θ and frequency at their third terminals.The second and third mixing means 220, 230 of the first mixer 200 willin operation receive the inverse of the first LO signal LO_(I) ⁻, i.e. aLO signal phase shifted by π radians. The second and third mixing means320, 330 of the second mixer 300 will in operation receive a second LOsignal LO_(Q) ⁺ having a second phase θ+π/2 and a frequencycorresponding to the first LO signal at their third terminals. The firstand fourth mixing means 310, 340 of the second mixer 300 will inoperation receive the inverse of the second LO signal LO_(Q) ⁻, i.e. aLO signal phase shifted π radians in relation to the second LO signal.

To avoid short circuit paths between the IF terminals, signal pathswitches are provided between the mixers and the RF terminals. Thus, thefirst mixer 200 comprises a first set of signal path switches 250, 260,270, 280, and the second mixer 300 comprises a second set of signal pathswitches 350, 360, 370, 380. In this embodiment, the signal pathswitches are provided by mixing means corresponding to the mixing means210-240, 310-340 of the mixers 200, 300. The first and fourth signalpath switches 250, 280 of the first mixer 200 correspond to the secondand third mixing means 320, 330 of the second mixer 300. The second andthird signal path switches 260, 270 of the first mixer 200 correspond tothe first and fourth mixing means 310, 340 of the second mixer 300. Thefirst and fourth signal path switches 350, 380 of the second mixer 300correspond to the first and fourth mixing means 210, 240 of the firstmixer 200. The second and third signal path switches 360, 370 of thesecond mixer 300 correspond to the second and third mixing means 220,230 of the second mixer 300.

A first terminal of the first and third signal path switches 250, 270,350, 370 is connected to the positive RF terminal, and a second terminalof said switches are connected to the first terminal of the first andthird mixing means 210, 230, 310, 330, respectively. Correspondingly, afirst terminal of the second and fourth signal path switches 260, 280,360, 380 is connected to the second terminal of the second and forthmixing means 220, 240, 320, 320, and a second terminal of said switchesis connected to the negative RF terminal, respectively.

Third terminal of the switches 250-280, 350-380 are connected to receiveLO signals correspondingly to their corresponding mixing means 210-240,310-340 of the mixers 200, 300. Thus, in this embodiment the switcheswill be a part of the frequency translation from a first to a secondfrequency.

The mixer arrangement is arranged to achieve quadrature mixing. Thus,two switches driven by the second LO signal LO_(Q) are for some timeintervals conducting simultaneously as two mixing means driven by thefirst LO signal LO_(I) are conducting.

FIG. 4 illustrates the local oscillator (LO) signals LO_(I) ⁺, LO_(I) ⁻,LO_(Q) ⁺, and LO_(Q) ⁻. LO_(I) and LO_(Q) can each have a first and asecond state, i.e. a specific frequency and phase, for turning a mixingmeans connected to the signal on or off. The first mixer 200 isconductive for a first and/or a second state of the first LO signalLO_(I). The second mixer 300 is conductive for a first and/or a secondstate of the second mixing signal. As can be seen from the scheme ofFIG. 4, two LO signals can be positive simultaneously, which correspondsto the gray areas. If the phases of the LO signals are chosen asdescribed above, LO_(I) ⁺ and LO_(Q) ⁻, LO_(I) ⁺ and LO_(Q) ⁺, LO_(Q) ⁺and LO_(I) ⁻, and LO_(I) ⁻ and LO_(Q) ⁻, respectively, will be positivesimultaneously, as is illustrated in FIG. 4. To avoid short circuits,the switches are therefore arranged such that in each potential pathbetween the IF terminals IF_(I) and IF_(Q) there are at least twoswitches controlled by signals having opposite phases, such as LO_(I) ⁺and LO_(I) ⁻, wherein there will be no risk of interference between theIF terminals. The switches 250-280 connected to the first mixer 200 arearranged to be conductive for the first and/or second state of the LO ormixing signal driving the second mixer 300. The switches 350-380connected to the second mixer 300 are arranged to be conductive for thefirst and/or second state of the LO or mixing signal driving the firstmixer 200. Thus, any short circuit between the mixers 200, 300 isavoided without substantially introducing any noise.

The embodiment of FIG. 3 illustrates one possible combination ofproviding the mixing means and the switches. There are a number ofcombinations, which will achieve the same result. Each of the switchesmay e.g. be interchanged with the mixing means to which it is connected.The combination that achieves the best performance has to be tested ineach specific case and should not be limited by the embodiment shown.

The mixer arrangement may be arranged to down convert an RF signalreceived as an input signal at the RF terminals to an IF output signalprovided at the IF terminals. Alternatively, an IF signal provided as aninput signal at the IF terminals may be up converted to an RF outputsignal provided at the RF terminals. Thus, the present invention may beincorporated in either a receiver or a transmitter for providingfrequency conversion from a first to a second frequency.

The present invention has been described above with reference tospecific embodiments. However, other embodiments than the abovedescribed are equally possible within the scope of the invention.Different method steps than those described above, performing the methodby hardware or software, may be provided within the scope of theinvention. The different features and steps of the invention may becombined in other combinations than those described. The invention isonly limited by the appended patent claims.

1. A quadrature mixer arrangement for converting a first signal at afirst frequency to a second signal at a second frequency, thearrangement having a first mixer operatively coupled to a first and asecond radio frequency (RF) terminal and a second mixer coupled inparallel with the first mixer and operatively coupled to the first andsecond RF terminal, wherein the first mixer is arranged to mix the firstsignal with a first mixing signal to provide the second signal; and thesecond mixer is arranged to mix the first signal with a second mixingsignal, whichs is out of phase with the first mixing signal, to providethe second signal, wherein the first mixer comprises: a first mixingmeans and a first signal path switch operatively connected in seriesbetween the first RF terminal and a first intermediate frequency (IF)terminal of the first mixer, wherein the first mixing means of the firstmixer is arranged to be controlled by the first mixing signal and thefirst signal path switch of the first mixer is arranged to be controlledby the second mixing signal; and a second mixing means and a secondsignal path switch operatively connected in series between the first RFterminal and a second IF terminal of the first mixer, wherein the secondmixing means of the first mixer is arranged to be controlled by theinverse of the first mixing signal and the second signal path switch ofthe first mixer is arranged to be controlled by the inverse of thesecond mixing signal; and the second mixer comprises: a first mixingmeans and a first signal path switch operatively connected in seriesbetween the first RF terminal and a first IF terminal of the secondmixer, wherein the first mixing means of the second mixer is arranged tobe controlled by the second mixing signal and the first signal pathswitch of the second mixer is arranged to be controlled by the inverseof the first mixing signal; and a second mixing means and a secondsignal path switch operatively connected in series between the first RFterminal and a second IF terminal of the second mixer, wherein thesecond mixing means of the second mixer is arranged to be controlled bythe inverse of the second mixing signal and the second signal pathswitch of the second mixer is arranged to be controlled by the firstmixing signal; whereby short circuits between said IF terminals of thefirst mixer and said IF terminals of the second mixer via the first RFterminal are prevented.
 2. The quadrature mixer arrangement according toclaim 1, wherein the first mixer further comprises: a third mixing meansand a third signal path switch operatively connected in series betweenthe second RF terminal and the second IF terminal of the first mixer,wherein the third mixing means of the first mixer is arranged to becontrolled by the first mixing signal and the third signal path switchof the first mixer is arranged to be controlled by the second mixingsignal; and a fourth mixing means and a fourth signal path switchoperatively connected in series between the second RF terminal and thefirst IF terminal of the first mixer, wherein the fourth mixing means ofthe first mixer is arranged to be controlled by the inverse of the firstmixing signal and the fourth signal path switch of the first mixer isarranged to be controlled by the inverse of the second mixing signal;and the second mixer further comprises: a third mixing means and a thirdsignal path switch operatively connected in series between the second RFterminal and the second IF terminal of the second mixer, wherein thethird mixing means of the second mixer is arranged to be controlled bythe second mixing signal and the third signal path switch of the secondmixer is arranged to be controlled by the inverse of the first mixingsignal; and a fourth mixing means and a fourth signal path switchoperatively connected in series between the second RF terminal and thefirst IF terminal of the second mixer, wherein the fourth mixing meansof the second mixer is arranged to be controlled by the inverse of thesecond mixing signal and the fourth signal path switch of the secondmixer is arranged to be controlled by the first mixing signal; wherebyshort circuits between said IF terminals of the first mixer and said IFterminals of the second mixer via the second RF terminal are prevented.3. The quadrature mixer arrangement according to claim 2, wherein eachof the mixing means and each of the signal path switches are provided asvoltage-controlled switches.
 4. The quadrature mixer arrangementaccording to claim 3, wherein the voltage controlled switches are NMOStransistors or PMOS transistors.
 5. The quadrature mixer arrangementaccording to claim 1, wherein each of the mixing means and each of thesignal path switches are provided as voltage-controlled switches.
 6. Thequadrature mixer arrangement according to claim 5, wherein the voltagecontrolled switches are NMOS transistors or PMOS transistors.
 7. Thequadrature mixer arrangement according to claim 1, wherein thequadrature mixer arrangement is provided as a transmitter mixer arrangedto receive the first signal as a quadrature IF signal at said IFterminals of the first and the second mixer, and arranged to output thesecond signal as an RF signal at said RF terminals.
 8. The quadraturemixer arrangement according to claim 1, wherein the quadrature mixerarrangement is provided as a transmitter mixer arranged to receive thethe first signal as an RF signal at said RF terminals, and arranged tooutput the second signal as a quadrature IF signal at said IF terminalsof the first and the second mixer.
 9. A wireless communication devicehaving a communication interface for wirelessly communicating with aremote communication device, comprising a quadrature mixer arrangementfor converting a first signal at a first frequency to a second signal ata second frequency, the arrangement having a first mixer operativelycoupled to a first and a second radio frequency (RF) terminal and asecond mixer coupled in parallel with the first mixer and operativelycoupled to the first and second RF terminal, wherein the first mixer isarranged to mix the first signal with a first mixing signal to providethe second signal; and the second mixer is arranged to mix the firstsignal with a second mixing signal, which is out of phase with the firstmixing signal, to provide the second signal, wherein the first mixercomprises: a first mixing means and a first signal path switchoperatively connected in series between the first RF terminal and afirst intermediate frequency (IF) terminal of the first mixer, whereinthe first mixing means of the first mixer is arranged to be controlledby the first mixing signal and the first signal path switch of the firstmixer is arranged to be controlled by the second mixing signal; and asecond mixing means and a second signal path switch operativelyconnected in series between the first RF terminal and a second IFterminal of the first mixer, wherein the second mixing means of thefirst mixer is arranged to be controlled by the inverse of the firstmixing signal and the second signal path switch of the first mixer isarranged to be controlled by the inverse of the second mixing signal;and the second mixer comprises: a first mixing means and a first signalpath switch operatively connected in series between the first RFterminal and a first IF terminal of the second mixer, wherein the firstmixing means of the second mixer is arranged to be controlled by thesecond mixing signal and the first signal path switch of the secondmixer is arranged to be controlled by the inverse of the first mixingsignal; and a second mixing means and a second signal path switchoperatively connected in series between the first RF terminal and asecond IF terminal of the second mixer, wherein the second mixing meansof the second mixer is arranged to be controlled by the inverse of thesecond mixing signal and the second signal path switch of the secondmixer is arranged to be controlled by the first mixing signal; wherebyshort circuits between said IF terminals of the first mixer and said IFterminals of the second mixer via the first RF terminal are prevented.10. The wireless communication device according to claim 9, wherein thefirst mixer further comprises: a third mixing means and a third signalpath switch operatively connected in series between the second RFterminal and the second IF terminal of the first mixer, wherein thethird mixing means of the first mixer is arranged to be controlled bythe first mixing signal and the third signal path switch of the firstmixer is arranged to be controlled by the second mixing signal; and afourth mixing means and a fourth signal path switch operativelyconnected in series between the second RF terminal and the first IFterminal of the first mixer, wherein the fourth mixing means of thefirst mixer is arranged to be controlled by the inverse of the firstmixing signal and the fourth signal path switch of the first mixer isarranged to be controlled by the inverse of the second mixing signal;and the second mixer further comprises: a third mixing means and a thirdsignal path switch operatively connected in series between the second RFterminal and the second IF terminal of the second mixer, wherein thethird mixing means of the second mixer is arranged to be controlled bythe second mixing signal and the third signal path switch of the secondmixer is arranged to be controlled by the inverse of the first mixingsignal; and a fourth mixing means and a fourth signal path switchoperatively connected in series between the second RF terminal and thefirst IF terminal of the second mixer, wherein the fourth mixing meansof the second mixer is arranged to be controlled by the inverse of thesecond mixing signal and the fourth signal path switch of the secondmixer is arranged to be controlled by the first mixing signal; wherebyshort circuits between said IF terminals of the first mixer and said IFterminals of the second mixer via the second RF terminal are prevented.11. The wireless communication device according to claim 10, whereineach of the mixing means and each of the signal path switches areprovided as voltage-controlled switches.
 12. The wireless communicationdevice according to claim 11, wherein the voltage controlled switchesare NMOS transistors or PMOS transistors.
 13. The wireless communicationdevice according to claim 9, wherein each of the mixing means and eachof the signal path switches are provided as voltage-controlled switches.14. The wireless communication device according to claim 13, wherein thevoltage controlled switches are NMOS transistors or PMOS transistors.15. The wireless communication device according to claim 9, wherein thequadrature mixer arrangement is provided as a transmitter mixer arrangedto receive the first signal as a quadrature IF signal at said IFterminals of the first and the second mixer, and arranged to output thesecond signal as an RF signal at said RF terminals.
 16. The wirelesscommunication device according to claim 9, wherein the quadrature mixerarrangement is provided as a transmitter mixer arranged to receive thethe first signal as an RF signal at said RF terminals, and arranged tooutput the second signal as a quadrature IF signal at said IF terminalsof the first and the second mixer.